In order to accelerate sampling, we use the recently developed OPES method.[1]}, [2]}
In OPES, like in metadynamics[3]}, [4]}, [5]}, [6]}, the bias is constructed on-the-fly with the help of periodically added Gaussians \(G(s,s_n)\)  that are functions of the chosen CVs \(s\)  and are centered at the CVs current \(s_n\)  value, where \(n\)  labels the \(n^{th}\)  deposition.
In metadynamics, the Gaussians are directly added to the bias potential \(V(s)\) . In OPES instead, the added Gaussians modify the equilibrium probability distribution \(P(s)\)  which in turn is related to the bias by:
\(V(s) = - \frac{1}{\beta }\log \frac{p^{\text{tg}}(s)}{P(s)}\) 
